Encased electrical apparatus with external heat radiator and method of making the same



1934- J. J. FRANK 1,947,196

ENCASED ELECTRICAL APPARATUS WITH EXTERNAL HEAT RADIATOR AND METHOD OF MAKING THE SAIE Filed July 15, 1931 Inventor; John J. Frank, b5 My Mm His ALtorneg.

Patented Feb. 13, 1934 UNITED STATES PATENT orricr.

John J. Frank, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Application July 15, 1931. Serial No. 551,012

4 Claims.

My invention relates to electrical apparatus such as a transformer or reactor of the type which is immersed in an insulating and cooling liquid within a casing provided with external heat radiators. The liquid used with such apparatus absorbs the heat produced by the apparatus while in operation and then circuiates through the ex ternal radiators where the heat is given up by the liquid and dissipated into the surrounding air, the liquid then returning into the casing of the apparatus to absorb more heat. Various forms of external radiators have been proposed and used, one of the commonest forms being a simple vertical tube with its ends curved and forming pipe connections which are welded into openings near the top and bottom of the apparatus casing. In accordance with previous practice in forming and assembling the casing and its radiators, the positions of the openings have been marked on the casing wall and the openings punched out usually before the wall has been shaped and while the sheet which was to form the wall was still fiat. The wall has then been shaped, the radiators assembled with their pipe connections in the wall openings and the joints sealed by welds on the inside of the casing. In order to form better and stronger welded joints, the ends of the pipe connections have often been flanged out against the inner surface of the easing wall before being welded. The marking of the positions of the openings in the casing and the punching of these openings has been done from the outer surface of the casing. The general object of the invention is to provide improved welded connections between the radiators and casing and an improved method for forming these welded connections.

The invention will be better understood from the following description taken in connection with the accompanying drawing in which Fig. l is a sectional view of a portion of a transformer with its casing having a heat radiator welded to the casing in accordance with the invention, and Figs. 2 and 3 are sectional views of the invention which are enlarged to shows details more clearly.

Like reference characters indicate similar parts in the difierent figures of the drawing.

The transformer 10, shown in Fig. 1, is im- 4 mersed in a body of insulating and cooling liquid 11 within a casing 12. The casing 12 is provided with the usual form of external tubular heat radiator 13 of which any desired number may of course be used to cool the liquid 11. It has heretofore been the practice to mark the positions of the openings for the tubes and then to punch the openings from the outer surface of the casing wall. In accordance with the present invention the marking of the positions of the openings and the punching of the openings is done from the inner surface of the casing wall. When the punch is forced through the casing wall to form an opening, particularly if the punch is not in good condition, the edge of the opening where the punch enters is more or less p5 rounded and a burr is formed on the other edge where the punch leaves the opening. Thus by punching the openings from the inner surface of the casing wall, the inner edges 14 of the openings are rounded and the ends of the pipe connections of the radiators are flanged over these rounded edges without injury. The burrs 15 formed by the punch are on the outer edges of the openings where they cannot cut into the bases of the flanges and thus injure and weaken them. After the 7:; ends of the pipe connections of the radiators have been flanged over the rounded edges of the openings and against the inner surface of the casing wall, they are sealed to the casing Wall by welds 16. Flanges of different widths may be used as desired, a wide flange being indicated in Fig. 2, and a narrow flange being indicated'in Fi 3.

The invention has been explained by describing and illustrating the assembly of a partticular form of external radiator and a transformer casing and the method of assembling the radiators and easing, but it will be apparent that changes may be made without departing from the spirit of the invention and the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

i. The method of assembling a radiator pipe connection and an electrical apparatus casing, said method including the steps of punching an opening through said casing from the inner surface thereof, whereby the inner edge of said opening is rounded, inserting said pipe connection through said opening, i'langing said pipe connection over said rounded edge of the opening, and welding said flange to said casing.

2. The method of assembling a radiator pipe connection and an electrical apparatus casing,- said method including the steps of punching an opening through said casing from the inner surface thereof, whereby the inner edge of said opening is rounded, inserting said pipe connection through said opening, fianging said pipe connection over said rounded edge of the opening and against the inner surface of said casing, and welding said flange to the inner surface of the casing.

3. The combination with an electrical apparatus casing having an outwardly punched opening with an inner rounded edge, of an external heat radiator with a connecting pipe extending through said opening, said pipe having an end flange extending outwardly over said rounded edge of the opening and welded to said casing. 

